Página 1 dos resultados de 92 itens digitais encontrados em 0.006 segundos

‣ A comparison of in-situ measurements and satellite remote sensing of underwater visibility

Museler, Erica A.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
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Approved for public release; distribution is unlimited.; SeaWiFS data converted to optical properties of the ocean in the form of vertical and horizontal underwater visibility products are compared to in-water diver and optical instrument measurements during the Model Diver Visibility (MoDiV) experiment. Results were collected from 19 to 21 August in the Mississippi Bight region of the United States. The SeaWiFS satellite data was processed with the Automated Processing System (APS), developed by the Naval Research Laboratory (Code 7333). APS converted radiance values into specific parameters studied: the beam attenuation coefficient, the diffuse attenuation coefficient, vertical visibility and horizontal visibility. These values were compared to the AC-9instrument, a-Beta instrument, Secchi disk and the observed visibilities from the divers. The results indicated that the beam attenuation coefficient and the diffuse attenuation coefficient are underestimated as compared to the in-situ measurements. These values then overestimate the vertical and horizontal visibility as compared to the Secchi disk and diver sightings. The visibility products from SeaWiFS should be used on an experimental basis for Naval Operational Planning. It is recommended that the use of in-water diver reports noting variability of SeaWiFS visibility product estimates are necessary for validation and offers feedback to the research and development field for algorithm improvement.

‣ Aerosol optical depth model assessment with high resolution multiple angle sensors

Martin, Joseph S.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
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Approved for public release, distribution is unlimited; This thesis assesses the performance of the Naval Postgraduate School Aerosol Optical Depth (NPS AOD) model utilizing very high spatial resolution QuickBird (QB) satellite data. QuickBird derived AOD results are compared to other satellite and ground based AOD results, specifically, AErosol RObotic NETwork (AERONET), MODerate resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging SpectroRadiometer (MISR), and Advanced Very High Resolution Radiometer (AVHRR). Data is collected around Sir Bu Nuair Island, United Arab Emirates in September 2004 as part of the UAE2 Campaign. Satellite measured radiances are calibrated and due to spatial resolution differences between sensors, modal radiances are calculated for areas matching the highest resolution sensor. The AOD model is based on AVHRR wavelengths; hence, the modal satellite measured radiances are linearly extrapolated to the effective wavelengths of AVHRR. Results show application of the NPS AOD model to QuickBird data yields findings that are consistent with other satellite and ground based retrievals. In general, the NPS AOD model works well for nadir and near-nadir view angles, but not for high zenith angles.

‣ Bathymetric mapping with QuickBird data

Densham, Martin P. J.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
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Two algorithms are used to determine bathymetry in the littoral region using QuickBird multispectral satellite observations. The algorithms determine water-leaving radiance and convert this to water depth values. The first algorithm uses a ratio of two wavebands and the second uses the sum of several wavebands. Relative bathymetric errors are determined for the clear water of Looe Key (USA) and the turbid water of Plymouth Sound (UK). Bathymetric measurements from LIDAR and chart data are compared to derived depths to assess their accuracies. An amended version of the ratio method is proposed for use in turbid water to improve accuracy. The results show that the standard ratio and turbidity algorithms have a relative error of 11.7% and 16.5% respectively in clear water. In turbid water the average error of the turbidity algorithm is 11.6% and the amended ratio algorithm average error is 13%.

‣ Aerosol scattering phase function retrieval from polar orbiting satellites

Wunder, Daniel P.
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
The retrieval of an aerosol scattering phase function using a multi-satellite technique is proposed. A total of 33 phase functions were derived from 18 smoke cases and 15 dust cases. Each case was interrogated using four to nine satellite passes over the aerosol in a two to four hour time frame. The radiance values for the Red and Near-Infrared (NIR) channels were combined with backscattering angles to determine the shape of the scattering phase function. The radiance values were input into the Naval Postgraduate School (NPS) aerosol model to determine optical depths and sample phase functions. A comparison was made between the actual phase functions retrieved and the NPS model phase functions. It was found that the phase functions for the smoke cases more closely matched the model phase functions than in the dust cases. Some conclusions could be drawn about the actual aerosol size and density distribution based on how well it matched the model phase function. Further analysis is necessary to define the exact size and number of the aerosol particles. Fully understanding the aerosol composition is crucial in determining its effects on military sensors and impacts to operations.

‣ Enhancement of the daytime GOES-based aircraft icing potential algorithm using MODIS

Alexander, Jeremy Brandon
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
Approved for public release, distribution is unlimited; In this thesis, a fuzzy logic algorithm is developed for the detection of potential aircraft icing conditions using the Moderate-Resolution Imaging Spectroradiometer (MODIS). The fuzzy MODIS algorithm is developed in a manner similar to the cloud mask currently used to process MODIS imagery. The MODIS icing potential detection algorithm uses thresholds for 8 channels in a series of 12 tests to determine the probability of icing conditions being present within a cloud. The MODIS algorithm results were compared to results of the GOES icing potential detection algorithm run on MODIS imagery for 4 cases. When compared to positive and icing pilot reports for the cases, the MODIS algorithm identified regions where icing was encountered more effectively than the GOES algorithm. Furthermore, the use of fuzzy thresholds on MODIS rather than the hard thresholds of the GOES algorithm allowed for less restrictive coverage of potential icing conditions, making the MODIS algorithm more reasonable in assessing all cloud regions for icing potential. The results found here are preliminary, as further statistical analysis with a larger validation dataset would be more effective. Algorithm details are provided in the appendix for reference.

‣ Remote sensing of the refractive environment above the marine stratocumulus-topped boundary layer

Derley, Dennis T.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
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400m), and overestimates their corresponding trapping layer depth by ~20%. For deeper boundary layer cases the duct strength was well represented, however, the trapping layer depth was over estimated by ~ 33%.

‣ Non linear internal waves modeling of their influence on acoustic mode energy fluctuations and characterization using SAR systems

Simon, Alban
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
Non Linear Internal Waves (NLIW) are ubiquitous and appear wherever a proper combination of stratified water, current and bathymetry occur. In recent years, they have also been proven of primary interest for acoustic oceanography, since they are known to play an important role in sound speed fluctuations in shallow waters. The predictability of acoustic variability caused by these waves has been somewhat limited, and largely based on direct numerical simulation. Through this project, we present a simple and computationally efficient analytic model based on coupled mode theory. For this purpose, narrow and broadband acoustic normal mode fluctuations in the 2001 South China Sea ASIAEX experiment are first examined. Then ASIAEX environmental data are used to characterize the space/time scales of NLIW sound speed structure. Finally, a comparison is conducted between the observed normal mode variability and the predictions from an analytic model utilizing the observed NLIW structure, such as its width, amplitude and speed. As the model proves to be very sensitive to these characteristics, an overview of the Synthetic Aperture Radar capabilities to retrieve them is also conducted. In this latter part of the project, particular attention is given to wind effects on SAR data.

‣ Enhancement of the daytime MODIS based icing potential using COAMPS and NOGAPS model data

Davidson, Richard Lee
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
In this thesis, NOGAPS and COAMPS model data are fused with Alexander (2005) algorithm to determine its usefulness in enhancing satellite-based aircraft icing analysis. This is a follow on to Cooper (2006) research where MM5 and ETA were used. Using historical NOGAPS and COAMPS data (T, Td and RH) accessed from the GODAE server, several storms from 2004 were fused with available MODIS imagery from the same storms to produce an enhanced icing product. Pilot reports (PIREPS) were used as a validation tool to determine where icing was taking place during the storms analyzed. A comparison was made between the MODIS-based icing potential and the modelbased icing potential. The two icing potentials were fused together to produce an enhanced icing product. Statistical analysis using ROC curves was performed on the various combinations to determine which product combination gave the best results. Two different available Tmap (Alexander and CIP) were used and had mixed results. Contrary to what Cooper (2006) found where weighting RH and the Alexander Tmap produced the best results; this study found that equal weighting of T and RH and the CIP Tmap produced the same or better results than weighting RH. This study also found that NOGAPS combined with the MODIS algorithm provide the best icing potential results.

‣ An assessment of the world wide merged cloud analysis using interactive graphics

Horsman, Stephen J.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
The Air Force Weather Agency (AFWA) uses the World Wide Merge Cloud Analysis (WWMCA) to display cloud amounts onto a hemispheric stereographic projection map. The goal of this study was to verify the WWMCA against real-time surface weather observations in the same spatial and temporal scale. The utilization of MapServer, a Geographic Information System (GIS) tool, to make these comparisons was essential in this study. The comparisons were 10 different Air Force bases across the continent of the United States for 16 days. Discrepancies existed between the drier climate and fair climate regions as compared to more active weather regions. Nellis and Travis AFB had higher number of verified observation as compared to the other eight bases. Maxwell AFB had the highest percentage of poorly verifying observations with 44% from the observer only results. Overall, the WWMCA did not verify well with a verification of 27% and a miss rate of 32%. Therefore, the Air Force Weather Agency (AFWA) needs to look at further improving cloud model output. This study shows some of the shortcomings of WWMCA cloud model data and the potential benefits to AFWA if improvements are made to cloud model output.

‣ A satellite based fog study of the Korean Peninsula

McDonald, David K.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
Fog has always been a difficult phenomenon to forecast. Its unpredictable nature and propensity to quickly decrease visibilities have had adverse effects on military operations for many years across the Korean peninsula. It is particularly difficult to prepare forecasts or plan operations for remote locations with limited fog detection ability. For detection at night, over large areas, and in remote locations, satellite observations are the best solution. This thesis used NASA MODIS satellite imagery to create an abbreviated climatology data set for remote areas across the Korean peninsula. Imagery from the Terra and Aqua near-polar orbiting satellites was used, providing four images per day: one daytime and one nighttime pass for each satellite. Two decision trees were developed to use as guidelines for fog detection by daytime and nighttime satellite images. It was not always possible to unambiguously determine if fog was in each scene, so various categories were created to supplement a fog or no fog decision. The four midseason months (October 2005, January 2006, April 2006, and July 2006), were analyzed to create a climatology database. The results are tabulated using different variables to make useful comparisons...

‣ A verification of optical depth retrievals from high resolution satellite imagery

Evans, Jack R.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
A new technique has been developed using high resolution satellite imagery to derive aerosol optical depths by measuring the difference of the radiances inside and outside of shaded regions Vincent (2006). This approach has shown promise as a new means of providing aerosol optical depth in regions that have proven difficult using more traditional means. Initial studies have been done primarily over desert/arid environments with some limited work over urban regions. This thesis takes the next step by focusing on the challenges that come along with using this technique in an urban environment and by exploring the relationship of how this technique is affected by different surface types. Four different surface types were examined, dirt, grass, pavement, and "other" which includes a random sampling of surfaces that are commonly found in urban environments. Three of these surface types act remarkably similar while grass surfaces deviate from the results seen with the other surfaces. Results from all the surfaces show a low bias which was not seen in the earlier study. This low bias can possibly be attributed to the aerosol model used when running the Shadow Method program, urban effects.

‣ Vertical variation of dust and its impact on the top of the atmosphere brightness temperature in the midwave infrared

Lucyk, Paul W.
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
The objective of this thesis is to investigate the vertical distribution of dust and its impact on the top of the atmosphere radiance and associated remotely sensed thermal variability in the midwave infrared wavelengths. Due to the inconsistent availability and coincidence of in-situ data with dust events, model data was used to identify the vertical dust regions. The Navy Aerosol Analysis and Prediction System global aerosol model was used to determine mass concentraion and vertical extent of dust. Mass concentration was converted to extinction and individual dust events were analyzed to characterize the vertical distribution, extinction, and optical depth. The average height was defined for specific dust regions of Iraq and Korea. This value was used to determine the impact of the dust layer on the top of the atmosphere radiance and brightness temperature in the wavelengths of interest. Radiative transfer software was used to determine the top of the atmosphere radiance of the modeled dust atmosphere. Resultant brightness temperature was calculated to obtain the thermal characteristics of the dust layer and associated atmosphere. The vertical distribution of the dust layer was varied with fixed atmospheric components to gain insight into the resultant variation of radiance and subsequent brightness temperature to provide a set of possible values for a regionally specific dust event.

‣ Extensible 3D (X3D) graphics clouds for geographic information systems

Murphy, Darren W.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
This research evaluates the production of three dimensional (3D) clouds for geospatial viewing programs such as Google Earth, NASA World Wind, and X3D Earth. This thesis took advantage of iso-standard X3D graphics and X3D Edit in conjunction with manually produced image textures to represent 3D clouds. While a 3D geospatial viewing might never completely characterize the current state of the atmosphere, a sufficiently realistic virtual 3D rendering can be created to present current sky coverage given adequate satellite and model data. Various visualization demonstration results are presented that can be rendered and navigated in real time. Further research and development is needed to match a cloud typing model output with a particular method of 3D cloud production. Data-driven adaptation and production of cloud models for web-based delivery is an achievable capability given continued research and development.

‣ Aerosol optical depth retrieval with AVIRIS data : a test Of Tafkaa

Rasure, James O.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
17.343486%
Approved for public release; distribution is unlimited.; Using solar wavelength radiance data obtained from the airborne AVIRIS instrument, during the LEO experiment, an analysis of aerosol optical depth (AOD) was completed using Tafkaa - a program developed by the Naval Research Laboratory (NRL). The objective of the analysis was to compare Tafkaa-retrieved AOD with AOD retrieved from SeaWiFS, and ground-based sun photometers. The intent of the study was to test enhanced AOD analysis using the hyperspectral coverage provided by AVIRIS. Comparisons between AOD retrieved by Tafkaa provided results consistent with SeaWiFS AOD retrieval and the AOD determined by ground-based sunphotometers in regions with minimal sediment and sun glint. A reliable sun glint mask was produced and applied to remove the effects of sun glint in the AVIRIS data.

‣ Depth derivation from the Worldview-2 satellite using hyperspectral imagery

Loomis, Michael J.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
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Approved for public release, distribution unlimited; The Worldview-2 satellite, scheduled for launch in 2009, will have a multispectral sensor with several additional spectral bands not available on current multispectral sensors. This research investigates the use of the additional yellow spectral band to derive bathymetry. A hyperspectral image acquired from the AVIRIS sensor was used as a substitute image for the Worldview-2 multispectral sensor. The image was processed using the Stumpf et al. (2003) "ratio method" to determine bathymetry in a section of Kaneohe Bay, Hawaii. Depths acquired using the green/blue, yellow/green and yellow/blue ratios were compared to ground truth bathymetry derived from a digital nautical chart. The results indicate that using the Stumpf et al. (2003) algorithm with yellow/green and yellow/blue ratios improves the accuracy of derived depths compared to depths derived using the green/blue ratio, especially in shallow waters.

‣ Stratocumulus and cloud-free reflectance from multi-spectral satellite measurements.

Tettlebach, Frederick M. Jr.; Durkee, Philip A.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
28.222295%

‣ Dr. Philip Durkee, Dean, School of Engineering and Applied Sciences, Biography

Fonte: Naval Postgraduate School, Monterey, CA. Publicador: Naval Postgraduate School, Monterey, CA.
Tipo: Biography
Português
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Biography and Awards of Dr. Philip Durkee, Dean, School of Engineering and Applied Sciences, Naval Postgraduate School, Monterey, CA.; Dr. Philip Durkee, Professor of Meteorology, was appointed the Dean of the Graduate School of Engineering and Applied Sciences (GSEAS) on January 1, 2012. Prof. Durkee earned his B.S. in Physics with distinction in 1978 from the University of Minnesota, and his M.S. (1980) and Ph.D. (1984) at Colorado State University. He joined the NPS Meteorology Department upon graduating from CSU, and served as Meteorology Department Chairman from 2004-2011.

‣ Clear-sky closure studies of lower tropospheric aerosol and water vapor during ACE-2 using airborne sunphotometer, airborne in-sity, space-borne, and ground-based measurements

Schmid, Beat; Livingston, John M.; Russell, Philip B.; Durkee, Philip A.; Jonsson, Haflidi H.; Collins, Donald R.; Flagan, Richard C.; Seinfeld, John H.; Gasso, Santiago; Hegg, Dean A.; Ostrom, Elisabeth; Noone, Kevin J.; Welton, Ellsworth J.; Voss, Kenne
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Português
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17.640793%
Tellus (ACE-2 Special Issue), 52B, 568-593; We report on clear-sky column closure experiments (CLEARCOLUMN) performed in the Canary Islands during the second Aerosol Characterization Experiment (ACE-2) in June/July 1997. We present CLEARCOLUMN results obtained by combining airborne sunphotometer and in-situ (optical particle counter, nephelometer, and absorption photometer) measurements taken aboard the Pelican aircraft, space-borne NOAA/AVHRR data and ground-based lidar and sunphotometer measurements. During both days discussed here, vertical profiles flown in cloud-free air masses revealed 3 distinctly different layers: a marine boundary layer (MBL) with varying pollution levels, an elevated dust layer, and a very clean layer between the MBL and the dust layer. A key result of this study is the achievement of closure between extinction or layer aerosol optical depth (AOD) computed from continuous in-situ aerosol size-distributions and composition and those measured with the airborne sunphotometer. In the dust, the agreement in layer AOD (l=380–1060 nm) is 3–8%. In the MBL there is a tendency for the in-situ results to be slightly lower than the sunphotometer measurements (10–17% at l=525 nm), but these differences are within the combined error bars of the measurements and computations.

‣ Aerosol optical depth retrieval using ATSR-2 and AVHRR data during TARFOX

Veefkind, J. Pepijn; de Leeuw, Gerrit; Durkee, Philip A.; Russell, Philip B.; Hobbs, Peter V.; Livingston, John M.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Artigo de Revista Científica
Português
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17.640793%
Satellite retrieved aerosol optical properties are compared to aircraft measurements for a case study during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). Two satellite instruments are used: the Along Track Scanning Radiometer 2 (ATSR-2) and the advanced very high resolution radiometer (AVHRR). The aerosol optical depth in the mid-visible (0.555 Jjm) retrieved from the ATSR-2 data agrees within 0.03 with colocated sunphotometer measurements. Also, the spectral behavior of the aerosol optical depth is retrieved accurately. Good correlation is found between aerosol optical depths for AVHRR channel 1 (0.64 Jjm) and sunphotometer derived values, but the satellite retrieved values are 0.05 to 0.15 lower. The Angstrom wavelength exponent is determined both from the ATSR-2 and the AVHRR data. The ATSR-2 derived Angstrom exponents are in good agreement with the values computed from the sunphotometer data. The Angstrom exponents determined from AVHRR data show very large variations. Both the ATSR-2 and the AVHRR aerosol optical depth images show a large gradient. Vertical profile data of temperature, relative humidity, and particle scattering indicate that this gradient is probably caused by changes in the dry aerosol properties...

‣ Clear-sky closure studies of lower tropospheric aerosol and water vapor during ACE-2 using airborne sunphotometer, airborne in-situ, space-borne, and ground-based measurements

Schmid, Beat; Livingston, John M.; Russell, Philip B.; Durkee, Philip A.; Jonsson, Haflidi H.; Collins, Donald R.; Flagan, Richard C.; Seinfeld, John H.; Gassó, Santiago; Hegg, Dean A.; Öström, Elisabeth; Noone, Kevin J.; Welton, Ellsworth J.; Voss, Ke
Fonte: Co-Action Publishing Publicador: Co-Action Publishing
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em /04/2000 Português
Relevância na Pesquisa
17.640793%
We report on clear-sky column closure experiments (CLEARCOLUMN) performed in the Canary Islands during the second Aerosol Characterization Experiment (ACE-2) in June/July 1997. We present CLEARCOLUMN results obtained by combining airborne sunphotometer and in-situ (optical particle counter, nephelometer, and absorption photometer) measurements taken aboard the Pelican aircraft, space-borne NOAA/AVHRR data and ground-based lidar and sunphotometer measurements. During both days discussed here, vertical profiles flown in cloud-free air masses revealed 3 distinctly different layers: a marine boundary layer (MBL) with varying pollution levels, an elevated dust layer, and a very clean layer between the MBL and the dust layer. A key result of this study is the achievement of closure between extinction or layer aerosol optical depth (AOD) computed from continuous in-situ aerosol size-distributions and composition and those measured with the airborne sunphotometer. In the dust, the agreement in layer AOD (λ=380–1060 nm) is 3–8%. In the MBL there is a tendency for the in-situ results to be slightly lower than the sunphotometer measurements (10–17% at λ=525 nm), but these differences are within the combined error bars of the measurements and computations.